A roll blind serves to block light beams, block external sight, absorb sounds, protect against the hot, and protect against the cold by downward unwinding or winding a screen in a roll shape. In addition to the practical use, the roll blind also serves to soften the hardness of a wall or glass and improve an interior beautiful sight by combinations of colors.
On the other hand, the known roll blind cannot properly adjust the intensity of light input from the outside by downward unwinding or winding the screen, and it is thus difficult to adjust the brightness.
Accordingly, a roll blind that can easily adjust the brightness was suggested in recent years. Examples of such a roll blind having a brightness adjusting function are disclosed in Korean Utility Model Registration Nos. 20-365028 and 20-0279166.
In such roll blinds having the brightness adjusting function, a transparent portion and an opaque portion are alternately arranged on the surface of a screen, the transparent portion and the opaque portion are formed in a stripe pattern, and the front transparent portions and the rear opaque portions are made to overlap with each other to adjust the intensity of light input from the outside, thereby adjusting the brightness.
However, the known roll blinds having the brightness adjusting function take much time for unwinding or winding a screen and are troublesome in operation, thereby deteriorating the convenience of use.
The known roll blinds having the brightness adjusting function do not guarantee the straightness of the stripe lines of the transparent portions and the opaque portions. Accordingly, the stripe lines of the transparent portions and the opaque portions overlapping with each other may be inclined to one side or curved to both sides, thereby damaging the external appearance.